Joseph Hartman

No genus or species (in the biological sense) exists in a vacuum, and human attempts to correctly classify new specimens in a way that reflects evolutionary relationships will necessarily fall short unless as much data as possible are taken into account. When specimen morphology or the sense of taxonomic history are incomplete, misnaming can occur, leading to a more complicated picture of the higher-order systematic relationships. This study aims to organize information in such a way that suspect fossil and modern specimen classifications can be identified and examined. The family Hyriidae of freshwater mussels exists in the southern hemisphere, preodminantly in Australia and South America, but there are examples of fossil material from the North American interior that have been classified as belonging to this family. Additionally, when fossil representatives of this family were first identified, the practice was to apply to them the names of extant genera and species-a practice tha...

... These brackish water deposits are intercalated with lignite-bearing, fluviola-custrine rocks of the Ludlow and Slope ... Paleocene boundary interval in northeastern Montana, and Nichols and Brown (1992) studied the Tullock Member of the Fort Union Formation in the Powder ...

... proposed need for the Slope Formation and its distinction from the Ludlow Formation in North ... freshwater environment inhabited by corbulid taxa in the Tongue River Member of western ... 2002, Lund, SP, Hartman, JH, and Banerjee, S., Magnetostratigraphy of interfingering Upper ...

Abstract:  A new spinicaudatan genus and species, Ethmosestheria mahajangaensis gen. et sp. nov., is described from the Anembalemba Member (Upper Cretaceous, Maastrichtian) of the Maevarano Formation, Mahajanga Basin, Madagascar. This is the first spinicaudatan reported from the post-Triassic Mesozoic of Madagascar. The new species is assigned to the family Antronestheriidae based on the cavernous or sievelike ornamentation on the carapace. Of well-documented Mesozoic spinicaudatan genera, Ethmosestheria mahajangaensis is most closely related to Antronestheria Chen and Hudson from the Great Estuarine Group (Jurassic) of Scotland. However, relatively poor documentation of the ornamentation of most Gondwanan Mesozoic spinicaudatan species precludes detailed comparison among taxa. Ethmosestheria mahajangaensis exhibits ontogenetic trends in carapace growth: a change in carapace outline from subcircular/subelliptical to elliptical, and from very wide juvenile growth bands to narrow adult growth bands. Ornamentation style, however, does not vary with ontogeny. Ethmosestheria mahajangaensis individuals lived in temporary pools in a broad channel-belt system within a semiarid environment; preserved desiccation structures on carapaces indicate seasonal drying out of pools within the river system. Specimens of Ethmosestheria mahajangaensis are preserved with exquisite detail in debris flow deposits; these are the first spinicaudatans reported from debris flow deposits. These deposits also contain a varied vertebrate fauna, including dinosaurs, crocodyliforms, turtles, and frogs. Rapid entombment of the spinicaudatan carapaces likely promoted early fossil diagenesis leading to highly detailed preservation.